Hi @JohnTransport. At this time, there is not a way to do this. I had thought that maybe you could do what you want with service modifiers, but at this time those are not part of the online booking flow. The only option you have is to have them book the services, then add the products and other items when checking them out.
I’d usually recommend submitting a feature request, but those seem have already been submitted and are being reviewed now.
